Process for forming fibrous sheets.



G. L. NORTON. rnocnss, r011 FORMING muons SHEETS. APPLICATION EQILBD'JAN. 29, 1910.

Patented Dec.27, 1910.

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G. L. NORTON. rnocnss r01; FORMING FIBROUS SHEETS. Arrmouxon Hum JAN.29, 1910.

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PROCESS FOR FQRMING FIBROUS SHEETS.

Specification of Letters Patent. Patented Dec. 27, EQEG.

Application filed January 29, 1910. Serial No. 540,730.

To all whomit may concern:

Be it known that 1, CHARLES LADD NOR- TON, a citizen of the UnitedStates, and resident of Hudson, in the county of Hillsboro and State ofNew Hampshire, have invented 'newand useful Improvements ,in Processesfor Forming Fibrous Sheets, of which the following is a specification.

This invention relates to the manufacture of sheets, slabs,and similararticles, of cement and fiber, or fiber-concrete, and consists in a newprocess of manufacture whereby such articles may bemade rapidly,continuously and economically.

Slabs or sheets of fiber and cement have been made singly in fiberpresses, and with success, using heavy pressure upon wet mush or pulpcomposed of fiber. and cementitious material, but though theimprovements in compounding and handling such material by thepress-process have reduced the cost and increased the output, theadvantages of a continuous process have not, so far as I am informed,been attained.

My invention'relat-es particularly to the manufacture of fire-proofsheets or slabs for structural and analogous purposes, in which asbestosfibers, or the similar fibers obtained by grinding serpentine rock and ahydraulic cement, constitute the ingredients 0 the fiber-concrete, 'andthe following specifications will be addressed to the manufacture ofasbestos fiber and hydraulic cement sheets or slabs. Suchcement-asbestos concrete nec essarily requires the presence of water toset the cement, and also requires considerable pressure to compact themass before the hydration, or setting, of the cement is completed.Attempts to produce compressedsheets by feeding a wet mass ofconcretepulp through rollers or other progressive pressure devices havebeen embarrassed by the persistence with which the wet pulp sticks tothe pressure devices and to other objects which come in contact with wetuncompressed pulp.

- My improved process which obviates the difllculties encountered inhandling wet uncompressed pulp, is characterized by a preliminarycontinuous or progressive dry pressing of a properly compounded mixtureof fiber and cement: the dry pressing comi pacts the'mixture and givesit consistency and integrity which, when setting liquid is afterwardadded, is effective to prevent the concrete mass from sticking toobjects with which it makes contact, so that a final wet continuous orprogressive pressing is easily applied. to give the finished product thenecessary density and strength for mechanical and structural uses, and aprogressive or continuous manufacture of'concreted sheets is madepractical and possible.

By availing myself of the facility of handling a dry-compressed mixtureof fiber and cement, I am enabled to produce compacted fiber concretesheets continuously and rapidly in contrast with the discontinu ous andslower filter press process, heretofore used in making fiber-cementsheets or slabs. In my new process, the preliminary dry-pressing isaccomplished by pressure devices which preferably work progressivelyalong a sheet or band of the dry-fiber-ceme'nt mixture, which travelsunder or between the pressure devices, so that, relatively speaking thepressure is a traveling pressure, exerted along a strip or band of thematerial. After the reliminary pressure has thus been applie thecompacted band is wetted with an appropriate setting liquid, and whensaturated thereby, is given a second and heavier traveling pressurewhich produces the necessary density in the final product.

In practice I preferto move the fiber-cement mixture by a continuousfeed, as a band under and between two sets of pressure rollers, one setto apply the traveling or progressive pressure to the band of thematerial while dry, the other set to apply pres sure to the band afterit has been wet. This process is preferably carried out with apparatussuch as is shown in the accompanying drawings, in which,

Figure 1 is a longitudinal elevation, partly in section, and Fig. 2 is aplan view of a machine which exemplifies inventions which form thesubject matter of an application for patent filed by me concurrentlyherewith and serially numbered 540,731.

The process herein described and claimed no he carried out by the aid ofother and specifically difierent' apparatus, but that shown the drawingsrepresents the elements of the machine which I have found to bepractically effective and.which I believe to be the best adapted for thepurpose.

This machine comprises two departments or divisions, one in which thematerial is handled dry, the other inv which it is handled wet. Thematerial is formed as a band or layer, which is conveyed first throughthe dry division, where it is dry-pressed, is then transferred to thewet division, wettedand wet pressed, and thence emerges in compactedcondition from the machine. Except for a short gap, the material iscarried and sustained by belt conveyers which move at uniform speed;while on the belt in the dry division the band of material is subjectedto rolling or traveling pressure, and is thereby compacted to suchconsistency that it projects itself without impairment of integrityacross the gap between the dry and wet divisions, being'sustained duringpart of its transit by a stationary bridge which has a smooth uppersurface.

The material which I have found to be best adapted to the construction.of fiberconcrete sheets orslabs is a mixture of short asbestos fiberswith Portland cement. The fibers may be obtained by grinding theserentine rock which forms the matrix of ong-fibered asbestos, and thenscreening or cleaning the The proportions of these solid ingredientswhich I recommend, are by Weight, one art fiber to, three parts cement.These are t oroughly mixed in dry condition and are then ready for themachine.

By adding from two to ten percent. (by weight) of finely ground quartzsand, to the dry mixture, the setting of the product is accelerated, andits strength increased.

Referring now to the drawings; represents a ho er into which the (1mixture M, refera y compounded as above stated, is ed. At the lower ordelivery end of the hopper there is rovided an adjustable gate Hby whicht e rate of delivery of material from the hopper may be regulated. Thelower end of'the opper H delivers the material to the endless travelingbelt B which may be composed of leather, canvas or other suitable beltmaterial. This belt B travels over and is-supported by'the latform ortable A which extends from t 0 guide roll C to the guide roll D, beinginterrupted or apertured at a. Pressure rolls Land U situated below andabove the table A respectively, operate-upon the material carriedby thebelt B through the aperture in the table at a. An adjustment or take.uproll is provided at R and this roll has bearings g at either end oftheroll so that the two end bearings of the roll may be independentlyadjusted. The lower pressure roll L fibrous pulp thus produced.v

pressure exerted by the roll U is mounted in fixed bearings at such aheight that the belt B passing across the aperture a in the table A istangent to the roll L. T he roll U is mounted in bearings on verticallyadjustable boxes g, these boxes being attached to rods 1 which at theirupper ends are surrounded by springs W and are threaded to receive nutsw. The springs W are compressible between the nuts to and the yoke Y sothat by screwing up the nuts 10, downward pressure may be brought tobear between the roll U and the roll L. The minimumpressure, under theseconditions, with which the upper roll U bears upon material betweenit'and the lower roll L- is that represented by the total weight of theupper roll and members attached to it. Parallel picker rolls S, 'S aremountedin bearings and extend across and above the table A between thehopper A and the pressure roll U. These pickers are arranged spirally asshown in Fig. 1 and rotate so as to brush off surplus material and todeliver. a band of material of substantially uniform thickness to passbetween the pressure rolls L and U; andalso, by reason of the spiralarrangement, to move surplus material to right and left off the belt Binto suitable receptacles (not shown) whence the surplus material may bereturned to the-hoper H. These picker rolls are driven from v the pulleyP by the belt p and the pulley P (Fig. 1). A short belt 32 joins thepulleys P, P of. which the latter has a larger diameter so that therolls S is driven at greater velocity than the roll S.

The mechanism shown and described forms the first division or de artmentof the machine in which the materlal is treated in a dry condition.

The other or wet division or department of the machine presents astructural resemblance to the first division and comprises the table A,a ertured at a, which su ports the endless belt B, the guiderolls D,adjustment roll R independentl adjusted at either end as by devices g, aower res sure roll L and an upper pressure ml the -,latter mounted in a-movable box; z which is provided with rods 1", springs adjusting nuts wand the yoke Y wherewith to increase or diminish the upon materialbetween it and the r0 ll L. The rolls and belts are driven by a pinion Gon the shaft with the pulley P, this pinion meshing with the spur gear Gwhich turns the roll U, this in turn meshing with gear Gr which n turnsthe. roll L, this in turn with the intermediate or idler gear G whichmeshes to drive the roll L whichiinmri V V which extends The sprinklerpipe V is provided with numerous apertures in its lower side, and inorder to insure uniform distribution of water over the belt B and thematerial on it, the sprinkler V is oscillated from side to side acrossthe belt B by means of the rocking lever V mounted in bearings V at oneside of the machine and taking into thecam V, mounted on the shaft withthe pinion G, and at its lower end forked between collars at V on thesprinkler pipe V. Thus, even if some of the apertures in the pipe Vshould become clogged, the vibration of the pipe will insure an evendistribution of water.

If the materials operated on are properly compounded and manipulated nodanger need be apprehended from the sticking of any of the material tothe rolls. N evertheless, to guard against'the contingency of materialsticking to the roll U I provide a scrape-r at m and a trough w toremove and catch material which may adhere to the roll U.

At the delivery end of the machine a cutting oft device may be providedsuch as indicated in the drawings wherein F represents cam-rollers and Ka vertically sliding chopper which descending at intervals upon thesheet of materialemerging from the machine will cut olf measuredlengths, depositing them, if desired, upon a platform L which may bemounted upon lowering de vices such as indicated at N (Fig. 2). i Thedriving mechanism for the cams F is not shown; any suitable connectionsto the gear train of the machine will serve.

That part of the machine which operates on the material after it hasbeen wet by the sprinkler pipe V constitutes what may be termed the wetdepartment or division of the machine.

Between the terminal rolls D. D of the dry division and the wet divisionrespectively, there is necessarily a short gap and this gap is for themost part filled by the bridge bar E which extends across the machine,having an upper surface preferably made smooth as by attaching a plateof polished metal) and which is substantially in the same plane as thetops of the belts B and B which are supported by the tables A and Arespectively, The top of the bridge bar E may with advantage be crownedor rounded. I

The operation of the machine is as follows: Assuming that finishedslabs-of fiber concrete three-sixteenths of .an inch thick are desired,the hopper gate H is so adjusted and the picker rolls S, S are soarranged that the feed of material and the combing and levelingoperation of the picker rolls dellvers a band or layer of this materialtraveling upon the belt B, which layer or I hand is aboutthree-quartersof an inch deep.

The pressure exerted between the rolls U and L is soadjusted that alayer or band of material in passing between these rolls is compactedwhile still dry to about one-half its original depth; that is to say, inthe case.

assumed for illustration, to a dry compressed band about three-eighthsof an inch deep. This compression confers upon the band or layer ofmaterial an integrity and firmness which enables it to project itselfacross the slight gap between the conveyer belt B and the bridge bar Eand also across the similar gap between the bridge bar E and the belt Bvand also enables the band of material toslide over the bridge bar Ewithout impairment of its smoothness, integrity and uniformity. On thusleaving the dry division of the machine, the layer of dry compressedmaterial is supplied with water from the vibrating sprinkler pipe V andthis Water penetrates to all parts of the layer. The rate of travel ofthe layer and therefore of the belts B and B and the distance betweenpipe V and roll U should be such that by the time any portion of thematerial reaches the pressure rolls U and L, the water supplied to itwill have thoroughly penetrated to the bottom of the layer.

The, pressure devices in the wet division of the material are soadjusted as to exert a pressure upon the wet layer of materialsufficient to compress it finally to a thickness of three-sixteenths ofan inch in the case assumed for illustration.

The action of the water upon the band of material previouslydrycompressed produces a visible compacting or contracting of the layereven before the rolls U, L operate upon it, so that when the materialsare properly compounded and the amount of water supplied isregulatedwithin the rules a of proportion hereinabove indicated, thetraveling pressure exerted by the rolls U and L adequately compacts thematerial without any considerable portion of it adhering to the roll U.4

The slabs or sheets cut from the continuouslyv progressing] band arepreferably stacked up in presses with sheets of metal there held undercompression until they are dry. Sheets or slabs of practically any'dessired length may be formed in the machine by the process above describedand will be found to have ample strength and consistency for structuraland other useful pur poses.

Certain precautions should be observed between the sheets offiber-concrete and 1 shall compact wide,

cations of pressures, first in the design of the operating parts of sucha machine as above described. 'The pressure rolls both in the wet anddry divisions of the machine should be of ample diameter; I have foundthat rolls 24 diameter serve the purpose well. The deree of pressureexerted between the pairs of rolls will depend upon the thickness andthe width of the sheet of material operated upon. In forming finishedsheets three-' sixteenths of an inch thick as above described, tlie bandor sheet being 18 inches I have found that a total pressure between therolls of the dry division of 150 pounds and between the rolls of the wetdivision of about 1000 pounds,are adequate to obtain the intendedresult. w

The combing action of the picker rolls S and S? in addition to levelingoff the layer of material, performs a useful function in combing thefibers and also in covering the upper fibers with the comminuted cement.Between the picker roll S and the roll U, the-asbestos fibers areseldom, if ever,

visibly discernible at the top of the band v of material.

The physical conditions to be secured for the practice of my invention,whatever may be the specific or subordinate variations in process orapparatus, are; progressive advance of the materials operated on,relatively to pressure devices, successive applito the material when ina substantially dry state, second to the material in a..we t state andin its preparatory compacted condition. It is of primary importance thatthe dry-pressing the mixture to such density d that after a settingliquid "is applied thereto,

dry department.

it will not stick topressure devices which operate on the wet mixture;in other words, the preliminary dry-pressing must be such as to producea density in the mixture which gives it cohesion superior to anytendency to adhere to the other objects-notably the pressure devices,.with which it comes in contact after being wet. Animportant, thoughrelatively a secondary physical condition is the provision of distinctpartment and doesnot encroach upon the For obvious reasons continuous ortraveling. pressure is preferable, and this involves substantiallyuniform and continuous feed; this however is another physical conditionof secondary value. The primar physical conditions afford a test bywhich equivalents may be known and recognized.

What I claim and desire to secure by Letters Patent is:

1. The process of forming sheetsof fiber inches in which travels along ra wet departments in the apparatus, by which the wetting liquid isconfined to-the wet deand cementitious material, which'consists in firstmaking a layer of minuted cementitious material, dry and" intermixed,then compacting the said layer, while still dry, then applying a liquidappropriate to the cementitiousmaterial, and thereafterfurther'compacting the wet layer.

2. The process of forming sheets of fiberconcrete which consists infirst making a layer of fiber and comminuted hydraulic cement, dry andintermixed, then compacting the said layer, while still dry, thenapplying a setting liquid to the dry-compacted layer, and thereafterfurther compacting the wet layer.-

3. The process of forming sheets of fiber concrete, which layer of drythoroughly intermixed fiber and comminuted cement, then conveying saidlayer as a-continuous band, subjecting said band, while dry, tocompacting pressure the dry-compressed band 'with a setting liquid, andthereafter subjecting the wet band to further traveling pressure.

4:. The process of formingsheets of fiber- .concrete, which consists infirst forming a layer ofdry thoroughly'intermixed asbestos fiber andhydraulic cement, then compacting said layer while still dry, to abouthalf its original thickness,

after compacting the layer to about one fourth of its originalthickness.

. 5. The process of forming sheets of fiberconcrete, which fiberandhydraulic cement, then conveying said layer. as a continuous band,subjecting said-band while dry to compacting pressure which travelsalong the band, thereby reducing it to about one half its originalthickness, then wetting the dry-compacted band witha setting liquid, andthereafter further compacting the band to about one fourth of itsoriginal thickness.-

6. The process of forming sheets of fiberconcrete which consists infirst forming a layer of comminuted hydraulic cement, then compactingthe said layer, while still dry, then,

applying a setting liquid to the dry-compacted layer, and thereafterfurther com; pacti'ng the wet layer. 7. The process of forming sheets offiberconcrete which COIISIStS'lH first forming a.

layer of dry thoroughly intermixed asbestos fiber and comminutedhydraulic cement, then conveying said layer as a continuous band,subjecting said band while dry to compacting pressure which travels alonthe band, then wetting the dry-compacted% with a setting liquid, andthereafter subthe fibers and com- 65 consists in first forming a 8the-band, then wetting 85 then applying a setting liquid to thedrycompacted layer, and there- 95 consists in first forming a layer ofdry thoroughly intermixed asbestos 100 dry intermixed asbestos fiber andand jecting the Wet band to further traveling pressure.

8. The process of forming sheets of fiberconcrete, which consists infirst forming a layer of dry thoroughly mixed fiber and comminutedcement, combing the surface of the layer while dry, then compacting thesaid layer, while still dry, then wetting the dry-compacted layer with asetting liquid,

and thereafter further compacting the wet layer.

9. The process of forming sheets of fiberconerete which consists infirst forming a layer of dry thoroughly intermixed asbestos fiber andhydraulic cement, the latter largely preponderatin compacting the layerWhile dry, then app ying a setting liquid to the dry-compacted layer,and thereafter further compacting the wet layer.

10. The process of forming sheets of fiberconcrete, which consists infirst forming a band of dry thoroughly intermixed asbestos fiber andhydraulic cement, the latter largely preponderating, subjecting saidband, while dry, to traveling compacting pressure, then applying asetting liquid thereto, and therelayer from sticking to pressure deviceswhen wet, then applying a setting liquid to the dry-compacted layer, andthereafter further compacting the wet layer.

12. The process of forming sheets of fiberconcrete, which consists infirst forming a layer of dry thoroughly intermixed asbestos fiber andhydraulic cement, then compacting said layer, while dry, to such densityas prevents the layer from sticking to pressure devices wh'en wet, thenapplying a setting liquid to the dry-compacted layer, and thereafterfurther compacting the Wet layer. Signed by me at Boston, Massachusettsthis twenty fourth day of January 1910.

CHARLES LADD NORTON. Witnesses:

ODEN Ronnn'rs, CHARLES D. WOODBERRY.

